Authentication
When it comes to authentication, there are some configurations that may be relevant
The apps APIs are access-controlled using Altinn Authorization. Requests to the APIs are authorized using the following information:
AltinnStudioRuntimecookieAuthorizationheader
Login Methods
Altinn Authorization supports different types of users, which is important to consider when developing custom functionality in an app.
- Users
- Can log in via the Altinn Portal or through an external ID-porten session
- Have User ID, Party ID, and user profile. Authentication level is always greater than 0
- Can represent other parties through party selection
- ID-porten token must be exchanged for an Altinn token via Altinn Authorization
- Organization
- Clients authenticated via Maskinporten
- Applies to organizations with an agreement and access to Maskinporten
- Maskinporten token must be exchanged for an Altinn token
- Cannot be used for much in an Altinn app, as organizations are not valid submitters (an organization cannot submit on behalf of itself)
- Service owner
- Clients authenticated via Maskinporten
- Applies to organizations registered as service owners in Altinn (and owners of the running app), who have also requested a service owner scope when authenticating in Maskinporten (
altinn:serviceowner) - Maskinporten token must be exchanged for an Altinn token
- Service owner is not a valid submitter, but depending on the XACML policy, service owners can start new instances and modify data in existing instances
- System user
- Clients authenticated via Maskinporten
- A system user is owned by an organization that is a customer/user of a supplier system. The system user is owned by the customer, while the system is owned by the supplier
- The supplier owns the Maskinporten client and authenticates. This allows the system to impersonate the system user (including rights the system user has been delegated from the customer)
- The apps API only accepts Maskinporten tokens that have been exchanged for an Altinn token (in the future, we will support Maskinporten tokens directly)
Organization from the list above.
There is no built-in restriction for these users, so if you want to block requests from enterprise users in your app,
this must be done manually. This can, for example, be achieved using ASP.NET Core middleware.Information in the app
The Altinn.App.Core library provides abstractions for retrieving information about the logged-in user.
By default, there are no restrictions on which user types an app accepts, but you can enforce such restrictions yourself in middleware or a validator.
Before version v8.6 of the app libraries, it was common to, for example, retrieve the user ID directly from HttpContext,
but this could yield unexpected results if the incoming request was authenticated as a system user.
From version v8.6 of Altinn.App.Core, the IAuthenticationContext and Authenticated types are available:
namespace Altinn.App.Core.Features.Auth;
public interface IAuthenticationContext
{
Authenticated Current { get; }
}
...
public abstract class Authenticated
{
public sealed class User : Authenticated { ... }
public sealed class SelfIdentifiedUser : Authenticated { ... }
public sealed class Org : Authenticated { ... }
public sealed class ServiceOwner : Authenticated { ... }
public sealed class SystemUser : Authenticated { ... }
}
The IAuthenticationContext interface can be used in custom code to check what type of user is logged in, and what information
is associated with them.
Limit access
Apps have different requirements for access. In some cases, you may want to restrict the use to specific authentication methods. There is currently no built-in configuration to restrict access based on authentication methods in an app, but this is being considered.
IAuthenticationContext.Current uses information about the logged-in user from ASP.NET Core’s authentication stack.
This means that the ASP.NET Core auth middleware must have run for you to get the correct information.
Auth middleware is added in UseAltinnAppCommonConfiguration. So if you want to access IAuthenticationContext.Current
in an ASP.NET Core middleware, it must be added after UseAltinnAppCommonConfiguration has been called.
All interfaces implemented in an app, such as IInstantiationValidator in the example below, run at a time
when authentication information is available, so it is completely safe there.✅ Altinn portal-users
Here is an example implementation of IInstantiationValidator that only allows instantiation by users logged in via the Altinn portal:
using System.Threading.Tasks;
using Altinn.App.Core.Features;
using Altinn.App.Core.Features.Auth;
using Altinn.App.Core.Models.Validation;
using Altinn.Platform.Storage.Interface.Models;
namespace Altinn.App.Core;
internal sealed class ValidateInstantiation(IAuthenticationContext authenticationContext) : IInstantiationValidator
{
public Task<InstantiationValidationResult?> Validate(Instance instance)
{
var authenticated = authenticationContext.Current;
switch (authenticated)
{
case Authenticated.User user:
if (!user.InAltinnPortal)
{
return Task.FromResult<InstantiationValidationResult?>(
new()
{
Message = "You must be logged in to the Altinn portal to create a new instance",
Valid = false,
}
);
}
return Task.FromResult<InstantiationValidationResult?>(null);
default:
return Task.FromResult<InstantiationValidationResult?>(
new()
{
Message = "This app only supports user logins via the Altinn portal",
Valid = false,
}
);
}
}
}
The same authorization can be enforced globally using ASP.NET Core middleware:
WebApplication app = builder.Build();
...
app.UseAltinnAppCommonConfiguration();
app.Use(
async (context, next) =>
{
var authenticationContext = context.RequestServices.GetRequiredService<IAuthenticationContext>();
var authenticated = authenticationContext.Current;
if (authenticated is not Authenticated.User { InAltinnPortal: true })
{
context.Response.StatusCode = StatusCodes.Status403Forbidden;
await context.Response.WriteAsJsonAsync(
new ProblemDetails
{
Title = "Forbidden",
Detail = "This app only supports users in the Altinn portal",
Status = StatusCodes.Status403Forbidden
}
);
return;
}
await next(context);
}
);
✅ System users
In this example, we only allow requests from system users:
WebApplication app = builder.Build();
...
app.UseAltinnAppCommonConfiguration();
app.Use(
async (context, next) =>
{
var authenticationContext = context.RequestServices.GetRequiredService<IAuthenticationContext>();
var authenticated = authenticationContext.Current;
if (authenticated is not Authenticated.SystemUser)
{
context.Response.StatusCode = StatusCodes.Status403Forbidden;
await context.Response.WriteAsJsonAsync(
new ProblemDetails
{
Title = "Forbidden",
Detail = "This app can only be used as a system user",
Status = StatusCodes.Status403Forbidden
}
);
return;
}
await next(context);
}
);
❌ Enterprise users
In this example, we block the deprecated enterprise users from Altinn 2:
WebApplication app = builder.Build();
...
app.UseAltinnAppCommonConfiguration();
app.Use(
async (context, next) =>
{
var authenticationContext = context.RequestServices.GetRequiredService<IAuthenticationContext>();
var authenticated = authenticationContext.Current;
if (authenticated is Authenticated.Org)
{
context.Response.StatusCode = StatusCodes.Status403Forbidden;
await context.Response.WriteAsJsonAsync(
new ProblemDetails
{
Title = "Forbidden",
Detail = "Enterprise users are not allowed in this app",
Status = StatusCodes.Status403Forbidden
}
);
return;
}
await next(context);
}
);